Q: Engine misses and losing power on 2003 Volkswagen Jetta

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Out of the blue this morning, the engine in my Jetta suddenly began running really rough and started "missing". It does this when idling - making me think it is going to stall, and then at speed, it was very hard to get her above 45mph - like she had no power. There is a strong smell from the tailpipe. The check engine light is on but I have not yet taken it to a garage to be diagnosed. Anyone have any ideas?
(1) Answer
There are many circumstances that can create the symptoms you are describing. RepairPal lists some of the more common reasons for drivability problems and the check engine light for your Jetta:

You can also read more about the check engine light in general:

But you will need professional diagnosis to narrow it down.